Field of the Invention
The present invention relates to a focus control apparatus and a control method for the same, and an image capturing apparatus, and in particular relates to a focus control apparatus capable of performing automatic focus adjustment (AF), and a control method for the same and an image capturing apparatus provided with the same.
Description of the Related Art
Single-lens reflex cameras are often provided with a focus detection system that uses a phase difference detection method to detect the focus state (defocus value) of the imaging optical system based on the phase difference between a pair of images formed by light that passed through the imaging optical system in an interchangeable lens. However, in this phase difference detection method, there is a risk of not being able to accurately detect the in-focus position due to the influence of the environment or the like at the time of imaging, and due to manufacturing error in single-lens reflex cameras and interchangeable lenses.
In order to solve this problem, there is an image capturing apparatus having a function (AF micro adjustment) for allowing the user to make desired micro adjustments to a correction value for the automatic focus adjustment function (AF). However, the AF micro adjustment contains a problem in that the operations of image capturing and checking need to be performed repeatedly in order to check whether or not the result of the user's micro adjustment is correct.
In order to resolve the above problem, Japanese Patent Laid-Open No. 2005-109621 discloses an image capturing apparatus that has a function in which focus bracket imaging is performed while associating the defocus values of the imaging lens with images, and an AF correction value is automatically calculated based on a defocus value associated with an image selected by the user from among a plurality of shot images.
However, according to the technique disclosed in Japanese Patent Laid-Open No. 2005-109621, an incorrect AF correction value is calculated due to a detection error of the defocus values associated with the images, which may degrade the detection precision of the defocus value.